In general terms, Bates was an authority on how the brain processes language. More specifically, Bates' research focused on child language acquisition, cross-linguistic language processing, and aphasia, investigating the cognitive, neural, and social factors subserving these processes. Through her research, Bates demonstrated that neural plasticity allows children with trauma to Broca's and Wernicke's areas to learn and use language normally.[citation needed]. Research in her lab also showed that adult aphasic patients' deficits were not specific to linguistic structures theorized to be localized to specific brain areas,[2] nor were they restricted to the linguistic domain.[3]

Some of Bates's other major contributions included demonstrating that distinct characteristics of different languages determine the way that the brain organizes this information and incorporates it during development, adulthood, and in cases of disease, and illuminating the profound and lasting links between language and evolutionarily more ancient non-linguistic skills. With Brian MacWhinney, Bates developed a model of language processing called the competition model, which views language acquisition as an emergentist phenomenon that results from competition between lexical items, phonological forms, and syntactic patterns, accounting for language processing on the synchronic, ontogenetic, and phylogenetic time scales.[citation needed]